Operation methods of communication node in network

ABSTRACT

Operation methods of a first communication node in a network, in particular, an Ethernet-based vehicle network, include: transmitting, by the first communication node to at least one communication node which is connected to the first communication node, a first frame requesting state information of a physical layer between the first communication node and the at least one communication node; receiving, by the first communication node from the at least one communication node, a second frame in response to the first frame; and identifying, by the first communication node, a state of the physical layer based on the second frame when the second frame is received.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims under 35 U.S.C. §119(a) the benefit of KoreanPatent Application No. 10-2015-0127142 filed on Sep. 8, 2015 in theKorean Intellectual Property Office (KIPO), the entire contents of whichare incorporated by reference herein.

BACKGROUND

1. Technical Field

The present disclosure relates generally to operation of a communicationnode in a network, and more specifically, to methods for analyzing astate of a physical layer and setting a communication path based on theanalyzed state of the physical layer.

2. Description of the Related Art

Along with the rapid digitalization of vehicle parts, the number andvariety of electronic devices installed within a vehicle have beenincreasing significantly. Electronic devices may currently be usedthroughout the vehicle, such as in a power train control system, a bodycontrol system, a chassis control system, a vehicle network, amultimedia system, and the like. The power train control system mayinclude an engine control system, an automatic transmission controlsystem, etc. The body control system may include a body electronicequipment control system, a convenience apparatus control system, a lampcontrol system, etc. The chassis control system may include a steeringapparatus control system, a brake control system, a suspension controlsystem, etc. The vehicle network may include a controller area network(CAN), a FlexRay-based network, a media oriented system transport(MOST)-based network, etc. The multimedia system may include anavigation apparatus system, a telematics system, an infotainmentsystem, etc.

Such systems and electronic devices constituting each of the systems areconnected via the vehicle network, which supports functions of theelectronic devices. For instance, the CAN may support a transmissionrate of up to 1 Mbps and may support automatic retransmission ofcolliding messages, error detection based on a cycle redundancyinterface (CRC), etc. The FlexRay-based network may support atransmission rate of up to 10 Mbps and may support simultaneoustransmission of data through two channels, synchronous datatransmission, etc. The MOST-based network is a communication network forhigh-quality multimedia, which may support a transmission rate of up to150 Mbps.

Meanwhile, the telematics system, the infotainment system, as well asenhanced safety systems of a vehicle require higher transmission ratesand system expandability. However, the CAN, FlexRay-based network, orthe like may not sufficiently support such requirements. The MOST-basednetwork may support a higher transmission rate than the CAN and theFlexRay-based network. However, costs increase to apply the MOST-basednetwork to all vehicle networks. Due to these limitations, anEthernet-based network may be considered as a vehicle network. TheEthernet-based network may support bi-directional communication throughone pair of windings and may support a transmission rate of up to 10Gbps.

The Ethernet-based vehicle network may include a plurality ofcommunication nodes. The communication node may be a gateway, a switch(or, bridge), an end node, etc. The communication node may be connectedto a counterpart communication node through a physical layer (e.g.,physical link). The communication node may transmit and receive a framethrough the physical layer. Here, reliability of the physical layershould be granted in order to successfully transmit and receive theframe. Therefore, methods for analyzing a state of the physical layerand setting a communication path based on the analyzed state of thephysical layer are necessary.

SUMMARY

The present disclosure provides a method and an apparatus for analyzinga state of a physical layer in an Ethernet-based vehicle network. Inaddition, embodiments of the present disclosure further provide a methodand an apparatus for setting a communication path based on the analyzedstate of the physical layer in the Ethernet-based vehicle network.

In accordance with the embodiments of the present disclosure, anoperation method of a first communication node in an Ethernet-basedvehicle network may be provided. The method may comprise transmitting,by the first communication node to at least one communication node whichis connected to the first communication node, a first frame requestingstate information of a physical layer between the first communicationnode and the at least one communication node; receiving, by the firstcommunication node from the at least one communication node, a secondframe in response to the first frame; and identifying, by the firstcommunication node, a state of the physical layer based on the secondframe when the second frame is received.

The state information may be at least one of signal to noise ratio (SNR)information and path loss information of the physical layer.

The first frame may include an indicator requesting the stateinformation of the physical layer. In addition, the first frame mayinclude transmission power information of the first frame.

The first frame may be transmitted in a broadcast manner.

The second frame may include at least one of SNR information and pathloss information of the physical layer, and the SNR information and thepath loss information may be measured based on the first frame. Inaddition, the second frame may include transmission power information ofthe second frame.

The first frame may be transmitted when transmission of the stateinformation of the physical layer is requested by an on-board diagnostic(OBD) device which is connected to the first communication node.

Here, each of the first frame and the second frame may be generatedbased on an Ethernet protocol.

In addition, the method may further comprise transmitting, by the firstcommunication node, a third frame including the identified stateinformation of the physical layer to an OBD device.

In addition, the method may further comprise determining, by the firstcommunication node, whether the identified state of the physical layeris satisfied with a predefined quality criterion; and when theidentified state of the physical layer is not satisfied with thepredefined quality criterion, transmitting, by the first communicationnode, a third frame including information of the physical layer which isnot satisfied with the predefined quality criterion to an OBD device.

In addition, the method may further comprise determining, by the firstcommunication node, whether the identified state of the physical layeris satisfied with a predefined quality criterion; and when theidentified state of the physical layer is not satisfied with thepredefined quality criterion, setting, by the first communication node,a communication path based on at least one physical layer except for thephysical layer which is not satisfied with the predefined qualitycriterion.

Further, in accordance with the embodiments of the present disclosure,an operation method of a first communication node in an Ethernet-basedvehicle network may be provided. The method may comprise receiving, bythe first communication node from a second communication node, a firstframe requesting state information of a physical layer between the firstcommunication node and the second communication node; and transmitting,by the first communication node, a second frame including stateinformation of the physical layer to the second communication node whenthe first frame is received.

The state information may be at least one of signal to noise ratio (SNR)information and path loss information of the physical layer.

The first frame may include an indicator requesting the stateinformation of the physical layer. In addition, the first frame mayinclude transmission power information of the first frame.

The second frame may include at least one of SNR information and pathloss information of the physical layer, and the SNR information and thepath loss information may be measured based on the first frame. Inaddition, the second frame may include transmission power information ofthe second frame.

The second communication may be a switch, and the first communicationnode may be an end node connected to the switch.

Here, each of the first frame and the second frame may be generatedbased on an Ethernet protocol.

According to the embodiments of the present disclosure, the state of thephysical layer (e.g., SNR, path loss, whether breaking of the physicallayer occurs, etc.) between the communication nodes can be identified.When measured SNR is less than a predefined SNR (or, when measured pathloss is more than a predefined path loss, when the physical layer isbroken), the communication path for transmitting and receiving the framecan be reset. Therefore, a performance of the vehicle network can beenhanced.

BRIEF DESCRIPTION OF DRAWINGS

Embodiments of the present disclosure will become more apparent bydescribing in detail embodiments of the present disclosure withreference to the accompanying drawings, in which:

FIG. 1 is a diagram showing a vehicle network topology according toembodiments of the present disclosure;

FIG. 2 is a diagram showing a communication node constituting a vehiclenetwork according to embodiments of the present disclosure;

FIG. 3 is a sequence chart showing an operation method of acommunication node according to embodiments of the present disclosure;

FIG. 4 is a block diagram showing an Ethernet-based vehicle network inwhich an operation method of a communication node is performed; and

FIG. 5 is block diagram showing embodiments of a frame used in anEthernet-based vehicle network.

It should be understood that the above-referenced drawings are notnecessarily to scale, presenting a somewhat simplified representation ofvarious preferred features illustrative of the basic principles of thedisclosure. The specific design features of the present disclosure,including, for example, specific dimensions, orientations, locations,and shapes, will be determined in part by the particular intendedapplication and use environment.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Hereinafter, embodiments of the present disclosure will be described indetail with reference to the accompanying drawings. As those skilled inthe art would realize, the described embodiments may be modified invarious different ways, all without departing from the spirit or scopeof the present disclosure. Further, throughout the specification, likereference numerals refer to like elements.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the disclosure.As used herein, the singular forms “a,” “an,” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof. As used herein, the term “and/or”includes any and all combinations of one or more of the associatedlisted items.

It is understood that the term “vehicle” or “vehicular” or other similarterm as used herein is inclusive of motor vehicles in general such aspassenger automobiles including sports utility vehicles (SUV), buses,trucks, various commercial vehicles, watercraft including a variety ofboats and ships, aircraft, and the like, and includes hybrid vehicles,electric vehicles, combustion, plug-in hybrid electric vehicles,hydrogen-powered vehicles and other alternative fuel vehicles (e.g.fuels derived from resources other than petroleum).

Although embodiments are described herein as using a plurality of unitsto perform the exemplary process, it is understood that the exemplaryprocesses may also be performed by one or plurality of modules.Additionally, it is understood that the term controller/control unitrefers to a hardware device that includes a memory and a processor. Thememory is configured to store the modules, and the processor isspecifically configured to execute said modules to perform one or moreprocesses which are described further below. Moreover, it is understoodthat the units or modules described herein may embody acontroller/control unit for controlling operation of the unit or module.

Further, control logic of the present disclosure may be embodied asnon-transitory computer readable media on a computer readable mediumcontaining executable program instructions executed by a processor,controller/control unit or the like. Examples of the computer readablemediums include, but are not limited to, ROM, RAM, compact disc(CD)-ROMs, magnetic tapes, floppy disks, flash drives, smart cards andoptical data storage devices. The computer readable recording medium canalso be distributed in network coupled computer systems so that thecomputer readable media is stored and executed in a distributed fashion,e.g., by a telematics server or a Controller Area Network (CAN).

Since the present disclosure may be variously modified and have severalembodiments, specific embodiments will be shown in the accompanyingdrawings and be described in detail in the detailed description. Itshould be understood, however, that it is not intended to limit thepresent disclosure to the specific embodiments but, on the contrary, thepresent disclosure is to cover all modifications and alternativesfalling within the spirit and scope of the present disclosure.

Relational terms such as first, second, and the like may be used fordescribing various elements, but the elements should not be limited bythe terms. These terms are only used to distinguish one element fromanother. For example, a first component may be named a second componentwithout being departed from the scope of the present disclosure and thesecond component may also be similarly named the first component. Theterm ‘and/or’ means any one or a combination of a plurality of relatedand described items.

When it is mentioned that a certain component is “coupled with” or“connected with” another component, it should be understood that thecertain component is directly “coupled with” or “connected with” to theother component or a further component may be located therebetween. Incontrast, when it is mentioned that a certain component is “directlycoupled with” or “directly connected with” another component, it will beunderstood that a further component is not located therebetween.

Unless specifically stated or obvious from context, as used herein, theterm “about” is understood as within a range of normal tolerance in theart, for example within 2 standard deviations of the mean. “About” canbe understood as within 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%,0.1%, 0.05%, or 0.01% of the stated value. Unless otherwise clear fromthe context, all numerical values provided herein are modified by theterm “about.”

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this disclosure belongs. Termssuch as terms that are generally used and have been in dictionariesshould be construed as having meanings matched with contextual meaningsin the art. In this description, unless defined clearly, terms are notideally, excessively construed as formal meanings.

Hereinafter, embodiments of the present disclosure will be described indetail with reference to the accompanying drawings. In describing thedisclosure, to facilitate the entire understanding of the disclosure,like numbers refer to like elements throughout the description of thefigures and the repetitive description thereof will be omitted.

FIG. 1 is a diagram showing a vehicle network topology according toembodiments of the present disclosure.

As shown in FIG. 1, a communication node included in the vehicle networkmay be a gateway, a switch (or bridge), or an end node. The gateway 100may be connected with at least one switch 110, 110-1, 110-2, 120, and130 and may be configured to connect different networks. For example,the gateway 100 may support connection between a switch which supports acontroller area network (CAN) (e.g., FlexRay, media oriented systemtransport (MOST), or local interconnect network (LIN)) protocol and aswitch which supports an Ethernet protocol. Each of the switches 110,110-1, 110-2, 120, and 130 may be connected to at least one of end nodes111, 112, 113, 121, 122, 123, 131, 132, and 133. Each of the switches110, 110-1, 110-2, 120, and 130 may interconnect the end nodes 111, 112,113, 121, 122, 123, 131, 132, and 133, and control at least one of endnodes 111, 112, 113, 121, 122, 123, 131, 132, and 133 connected to theswitch.

The end nodes 111, 112, 113, 121, 122, 123, 131, 132, and 133 mayinclude an electronic control unit (ECU) configured to control varioustypes of devices mounted within a vehicle. For example, the end nodes111, 112, 113, 121, 122, 123, 131, 132, and 133 may include the ECUincluded in an infotainment device (e.g., a display device, a navigationdevice, and an around view monitoring device).

The communication nodes (e.g., a gateway, a switch, an end node, or thelike) included in the vehicle network may be connected in a startopology, a bus topology, a ring topology, a tree topology, a meshtopology, etc. In addition, the communication nodes of the vehiclenetwork may support the CAN protocol, the FlexRay protocol, the MOSTprotocol, the LIN protocol, or the Ethernet protocol. Embodiments of thepresent disclosure may be applied to the foregoing network topologies.The network topology to which embodiments of the present disclosure maybe applied is not limited thereto and may be configured in various ways.

FIG. 2 is a diagram showing a communication node constituting a vehiclenetwork according to embodiments of the present disclosure. Notably, thevarious methods discussed herein below may be executed by a controllerhaving a processor and a memory.

As shown in FIG. 2, a communication node 200 of a network may include aPHY layer unit 210 and a controller unit 220. In addition, thecommunication node 200 may further include a regulator (not shown) forsupplying power. In particular, the controller unit 220 may beimplemented to include a medium access control (MAC) layer. A PHY layerunit 210 may be configured to receive or transmit signals from or toanother communication node. The controller unit 220 may be configured tocontrol the PHY layer unit 210 and perform various functions (e.g., aninfotainment function, etc.). The PHY layer unit 210 and the controllerunit 220 may be implemented as one system on chip (SoC), oralternatively may be implemented as separate chips.

Further, the PHY layer unit 210 and the controller unit 220 may beconnected via a media independent interface (MII) 230. The MII 230 mayinclude an interface defined in the IEEE 802.3 and may include a datainterface and a management interface between the PHY layer unit 210 andthe controller unit 220. One of a reduced MII (RMII), a gigabit MII(GMII), a reduced GMII (RGMII), a serial GMII (SGMII), a 10 GMII (XGMII)may be used instead of the MII 230. A data interface may include atransmission channel and a reception channel, each of which may have anindependent clock, data, and a control signal. The management interfacemay include a two-signal interface, one signal for the clock and onesignal for the data.

Particularly, the PHY layer unit 210 may include a PHY layer interfaceunit 211, a PHY layer processor 212, and a PHY layer memory 213. Theconfiguration of the PHY layer unit 210 is not limited thereto, and thePHY layer unit 210 may be configured in various ways. The PHY layerinterface unit 211 may be configured to transmit a signal received fromthe controller unit 220 to the PHY layer processor 212 and transmit asignal received from the PHY layer processor 212 to the controller unit220. The PHY layer processor 212 may be configured to execute operationsof the PHY layer interface unit 211 and the PHY layer memory 213. ThePHY layer processor 212 may be configured to modulate a signal to betransmitted or demodulate a received signal. The PHY layer processor 212may be configured to control the PHY layer memory 213 to input or outputa signal. The PHY layer memory 213 may be configured to store thereceived signal and output the stored signal based on a request from thePHY layer processor 212.

The controller unit 220 may be configured to monitor and control the PHYlayer unit 210 using the MII 230. The controller unit 220 may include acontroller interface unit 221, a controller processor 222, a main memory223, and a sub memory 224. The configuration of the controller unit 220is not limited thereto, and the controller unit 220 may be configured invarious ways. The controller interface unit 221 may be configured toreceive a signal from the PHY layer unit 210 (e.g., the PHY layerinterface unit 211) or an upper layer (not shown), transmit the receivedsignal to the controller processor 222, and transmit the signal receivedfrom the controller processor 222 to the PHY layer unit 210 or upperlayer. The controller processor 222 may further include an independentmemory control logic or an integrated memory control logic forcontrolling the controller interface unit 221, the main memory 223, andthe sub memory 224. The memory control logic may be implemented to beincluded in the main memory 223 and the sub memory 224 or may beimplemented to be included in the controller processor 222.

Further, each of the main memory 223 and the sub memory 224 may beconfigured to store a signal processed by the controller processor 222and may be configured to output the stored signal based on a requestfrom the controller processor 222. The main memory 223 may be a volatilememory (e.g., a random access memory (RAM)) configured to temporarilystore data required for the operation of the controller processor 222.The sub memory 224 may be a non-volatile memory in which an operatingsystem code (e.g., a kernel and a device driver) and an applicationprogram code for performing a function of the controller unit 220 may bestored. A flash memory having a high processing speed, a hard disc drive(HDD), or a compact disc-read only memory (CD-ROM) for large capacitydata storage may be used as the non-volatile memory. Typically, thecontroller processor 222 may include a logic circuit having at least oneprocessing core. A core of an Advanced RISC Machines (ARM) family or acore of an Atom family may be used as the controller processor 222.

A method performed by a communication node and a correspondingcounterpart communication node in a vehicle network will be describedbelow. Although the method (e.g., signal transmission or reception)performed by a first communication node will be described below, themethod is applicable to a second communication node that corresponds tothe first communication node. In other words, when an operation of thefirst communication node is described, the second communication nodecorresponding thereto may be configured to perform an operation thatcorresponds to the operation of the first communication node.Additionally, when an operation of the second communication node isdescribed, the first communication node may be configured to perform anoperation that corresponds to an operation of a switch.

FIG. 3 is a sequence chart showing an operation method of acommunication node according to embodiments of the present disclosure,and FIG. 4 is a block diagram showing an Ethernet-based vehicle networkin which an operation method of a communication node is performed.

As shown FIGS. 3 and 4, the Ethernet-based vehicle network may include aplurality of switches 410, 420, 430, and 440 and a plurality of endnodes 420-1, 420-2, 430-1, 430-2, 440-1, and 440-2. Here, each of theplurality of switches 410, 420, 430, and 440 and the plurality of endnodes 420-1, 420-2, 430-1, 430-2, 440-1, and 440-2 may be the foregoingcommunication node shown in FIG. 2. The switch1 410 may connect to eachof the switch2 420 and the switch3 430 through a physical layer (e.g.,physical link) in a one-to-one manner, and transmit or receive a frameto or from each of the switch2 420 and the switch3 430 through thephysical layer. Here, a physical layer between the switch1 410 and theswitch2 420 may be referred to as a “PL-1,” and a physical layer betweenthe switch1 410 and the switch3 430 may be referred to as a “PL-2.”Also, The switch1 410 may connect to an on-board diagnostic (OBD) device400 through a physical layer in the one-to-one manner. The OBD device400 may be used for diagnosing a state of the communication node, astate of the physical layer between the communication nodes included inthe Ethernet-based vehicle network, etc.

The switch2 420 may connect to the switch1 410, the switch4 440, the endnode1 420-1, and the end node2 420-2 through a physical layer in theone-to-one manner, and transmit or receive a frame to or from each ofthe switch1 410, the switch4 440, the end node1 420-1, and the end node2420-2 through the physical layer. Here, a physical layer between theswitch2 420 and the end node1 420-1 may be referred to as a “PL-3,” aphysical layer between the switch2 420 and the end node2 420-2 may bereferred to as a “PL-4,” and a physical layer between the switch2 420and the switch4 440 may be referred to as a “PL-5.”

The switch3 430 may connect to the switch1 410, the switch4 440, the endnode3 430-1, and the end node4 430-2 through a physical layer in theone-to-one manner, and transmit or receive a frame to or from each ofthe switch1 410, the switch4 440, the end node3 430-1, and the end node4430-2 through the physical. Here, a physical layer between the switch3430 and the end node3 430-1 may be referred to as a “PL-6,” a physicallayer between the switch3 430 and the end node4 430-2 may be referred toas a “PL-7,” and a physical layer between the switch3 430 and theswitch4 440 may be referred to as a “PL-8.”

The switch4 440 may connect to the switch2 420, the switch3 430, the endnode5 440-1, and the end node6 440-2 through a physical layer in theone-to-one manner, and transmit or receive a frame to or from each ofthe switch2 420, the switch3 430, the end node5 440-1, and the end node6440-2 through the physical layer. Here, a physical layer between theswitch4 440 and the end node5 440-1 may be referred to as a “PL-9,” anda physical layer between the switch4 440 and the end node6 440-2 may bereferred to as a “PL-10.”

The Ethernet-based vehicle network in which operation methods of thecommunication node according to embodiments of the present disclosure isnot limited thereto, and the operation methods of the communication nodeaccording to embodiments of the present disclosure may be performed invarious Ethernet-based vehicle networks.

The switch1 410 may be a communication node having an analysis functionof the state of the physical layer, a set function of a communicationpath, etc. The switch1 410 may generate a first frame requesting stateinformation of the physical layer. Here, when transmission of the stateinformation of the physical layer is requested by the OBD device 400,the switch1 410 may generate the first frame. Alternatively, the switch1410 may generate the first frame regardless of the request of the OBDdevice 400.

The state information may include signal to noise ratio (SNR)information, path loss information of the physical layer, etc. Inaddition, the state information may further include a result which isdetermined based on at least one of the SNR information and the pathloss of the physical layer. The result may be a normal state indicatingthat the physical layer is satisfied with a predefined quality criterionor a fault state indicating that the physical layer is not satisfiedwith the predefined quality criterion. In addition, when the path lossinformation of the physical layer is requested by the first frame, thefirst frame may further include transmission power information of thefirst frame to be used for measuring the path loss.

The first frame may include an indicator requesting the stateinformation of the physical layer. For example, when the indicatorincluded in the first frame is set to binary numeral “0,” the indicatormay indicate that the state information of the physical layer is notrequested. When the indicator included in the first frame is set tobinary numeral “1,” the indicator may indicate that the stateinformation of the physical layer is requested. For other example, whenthe indicator included in the first frame is set to binary numeral “00,”the indicator may indicate that the state information of the physicallayer is not requested. When the indicator included in the first frameis set to binary numeral “01,” the indicator may indicate that the SNRinformation of the physical layer is requested. When the indicatorincluded in the first frame is set to binary numeral “10,” the indicatormay indicate that the path loss information of the physical layer isrequested. When the indicator included in the first frame is set tobinary numeral “11,” the indicator may indicate that both of the SNRinformation and the path loss information of the physical layer arerequested. Configurations of the indicator are not limited thereto, andthe indicator may be configured in various ways.

Meanwhile, a structure of the frame (e.g., first frame, second frame,third frame, fourth frame, fifth frame, etc.) used in the operationmethods of the communication node according to the present disclosuremay be as follows.

FIG. 5 is block diagram showing embodiments of a frame used in anEthernet-based vehicle network.

As shown in FIG. 5, a frame 500 may include a PHY header, a MAC frame,and a frame check sequence (FCS) field 508. The MAC frame may begenerated by the controller unit 220 of the communication node 200. ThePHY header may include a preamble field 501 and a start frame delimiter(SFD) field 502. A size of the preamble 501 may be 7 octets and be usedfor timing synchronization. The SFD field 502 may have a sequence of“10101011.”

The MAC frame may be located after the SFD field 502. The MAC frame mayinclude only a MAC header, or include a MAC header and a logic linkcontrol (LLC) frame. The MAC header may include a destination address(DA) field 503, a source address (SA) field 504 and a length/type field505. A size of the DA field 503 may be 6 octets and includeidentification information (e.g., MAC address) of the communication nodewhich receives a corresponding MAC frame. A size of the SA field 504 maybe 6 octets and include identification information (e.g., MAC address)of the communication node which transmits a corresponding MAC frame.

A size of the length/type field 505 may be 2 octets and indicate alength of a data field 506 or an Ethernet type supported by thecommunication node which transmits a corresponding protocol-based frame500. For example, when a first octet value included in the length/typefield 505 is less than or equal to decimal number 1500, the length/typefield 505 may indicate the length of the data field 506. When the firstoctet value included in the length/type field 505 is equal to or greaterthan decimal number 1536, the length/type field 505 may indicate theEthernet type. The LLC frame may include the data field 506. Inaddition, the LLC frame may further include a pad field 507 if necessary(e.g., in order to satisfy a minimum size of the MAC frame). Here, thepad field 507 may be added behind the data field 506.

Referring to FIGS. 3 and 4, each of the indicator and the transmissionpower information may be included in at least one of the MAC header andthe data field 506 of the first frame. The switch1 410 may transmit thefirst frame to the switch2 420 and the switch3 430 (S300). In this case,the switch1 410 may transmit the first frame in a broadcast manner of amulticast manner. The first frame may be transmitted periodically ornon-periodically.

Each of the switch2 420 and the switch3 430 may receive the first framefrom the switch1 410. The switch2 420 may identify the request of thestate information of the physical layer by receiving the first framefrom the switch1 410 and identify the state of the PL-1. In this case,the switch2 420 may operate depending on a type of the state informationof the physical layer requested by the first frame. For example, whenthe SNR information of the physical layer is requested, the switch2 420may measure the SNR of the PL-1 based on the received first frame andgenerate a second frame including the measured SNR information of thePL-1. Here, the measured SNR information of the PL-1 may be included inat least one of the MAC header and the data field 506 of the secondframe. Alternatively, the switch2 420 may generate the second frame,which does not include the SNR information of the PL-1, in simpleresponse to the first frame so that the SNR of the PL-1 is measured bythe switch1 410.

When the path loss information of the physical layer is requested, theswitch2 420 may measure the path loss of the PL-1 (e.g., differencebetween transmission power of the first frame and reception power of thefirst frame) based on the transmission power information included in thefirst frame and generate the second frame including the measured pathloss information of the PL-1. Here, the measured path loss informationof the PL-1 may be included in at least one of the MAC header and thedata field 506 of the second frame. Alternatively, when the transmissionpower information of the first frame is not included in the first frame,the switch2 420 may generate a second frame including transmission powerinformation of the second frame so that the path loss of the PL-1 ismeasured based on the second frame by the switch1 410. Here, thetransmission power information may be included in at least one of theMAC header and the data field 506 of the second frame.

When both of the SNR information and the path loss information of thephysical layer are requested, the switch2 420 may perform the foregoingall operations. Also, the switch2 420 may determine the state of thePL-1 based on the measured SNR or path loss of the PL-1. For example,when the SNR of the PL-1 is satisfied with the predefined qualitycriterion (e.g., the SNR of the PL-1 is more than a minimum SNR requiredfor quality of service (QoS)) or the path loss of the PL-1 is satisfiedwith the predefined quality criterion (e.g., the path loss of the PL-1is less than a maximum path loss required for QoS), the switch2 420 maydetermine that the state of the PL-1 is the normal state. In an oppositecase to the foregoing description, the switch2 420 may determine thatthe state of the PL-1 is the fault state. The switch2 420 may generatethe second frame including the determined result of the state of thePL-1.

The switch2 420 may transmit the second frame which is generated basedon the foregoing manner to the switch1 410 (S301).

The switch1 410 may receive the second frame in response to the firstframe from the switch2 420 and identify the state of the PL-1 based onthe received second frame. For example, the switch1 410 may obtain atleast one of the SNR information and the path loss information of thePL-1 from the second frame and identify the state (e.g., normal state orfault state) of the PL-1 based on the identified information.Alternatively, when the transmission power information of the secondframe is obtained from the second frame, the switch1 410 may measure thepath loss of the PL-1 based on the obtained information (e.g., thetransmission power information) and identify the state of the PL-1 basedon the measured path loss of the PL-1. Alternatively, when the secondframe in simple response to the first frame is received, the switch1 410may measure the SNR of the PL-1 based on the received second frame andidentify the state of the PL-1 based on the measured SNR of the PL-1.Alternatively, when the second frame includes information indicatingwhether the state of the PL-1 is the normal state or the fault state,the switch1 410 may identify the state of the PL-1 based on theinformation included in the second frame. On the other hand, when thesecond frame in response to the first frame is not received in apredefined time from the switch2 420, the switch1 410 may determine thatthe state of the PL-1 is a breaking state (e.g., the PL-1 is broken).

Meanwhile, the switch3 430 may identify that the state information ofthe physical layer is requested by receiving the first frame from theswitch1 410. In this case, the switch3 430 may operate similar to theforegoing operations of the switch2 420. For example, the switch3 430may generate the second frame including the state information (e.g., SNRinformation, path loss information, information indicating the normalstate, information indicating the fault state, etc.) of the PL-2 orinformation used for measuring the path loss of the PL-2. Alternatively,the switch3 430 may generate the second frame in simple response to thefirst frame. The switch3 430 may transmit the generated second frame tothe switch1 410.

The switch1 410 may receive the second frame in response to the firstframe from the switch3 430 and identify the state of the PL-2 based onthe received second frame. For example, the switch1 410 may identify thestate of the PL-2 similar to the foregoing method for identifying thestate of the PL-1. On the other hand, when the second frame in responseto the first frame is not received in the predefined time from theswitch3 430, the switch1 410 may determine that the state of the PL-2 isthe breaking state (e.g., the PL-2 is broken).

Meanwhile, the switch2 420 may generate the first frame requesting thestate information of the physical layer after transmitting the secondframe and transmit the generated first frame to communication nodes(e.g., end node1 420-1, end node2 420-2, and switch4 440) which areconnected to the switch2 420 (S302). In this case, the switch2 420 maytransmit the first frame in the broadcast manner or the multicastmanner. The first frame may include the indicator requesting the stateinformation of the physical layer. In addition, the first frame mayfurther include the transmission power information of the first frame.Here, each of the indicator and the transmission power information maybe included in at least one of the MAC header and the data field 506 ofthe first frame. The first frame transmitted from the switch2 420 may beidentical to the first frame transmitted from the switch1 410.

Each of the end node1 420-1, the end node2 420-2, and the switch4 440may receive the first frame from the switch2 420. The end node1 420-1may identify that the state information of the physical layer isrequested by receiving the first frame from the switch2 420 and identifythe state of the PL-3. In this case, the end node1 420-1 may operatedepending on the type of the state information of the physical layerrequested by the first frame. For example, when the SNR information ofthe physical layer is requested, the end node1 420-1 may measure the SNRof the PL-3 based on the received first frame and generate the secondframe including the measured SNR information of the PL-3. Here, themeasured SNR information of the PL-3 may be included in at least one ofthe MAC header and the data field 506 of the second frame.Alternatively, the end node1 420-1 may generate the second frame, whichdoes not include the SNR information of the PL-1, in simple response tothe first frame so that the SNR of the PL-3 is measured by the switch2420.

When the path loss information of the physical layer is requested, theend node1 420-1 may measure the path loss of the PL-3 (e.g., differencebetween transmission power of the first frame and reception power of thefirst frame) based on the transmission power information included in thefirst frame and generate the second frame including the measured pathloss information of the PL-3. Here, the measured path loss informationof the PL-3 may be included in at least one of the MAC header and thedata field 506 of the second frame. Alternatively, when the transmissionpower information of the first frame is not included in the first frame,the end node1 420-1 may generate the second frame including transmissionpower information of the second frame so that the path loss of the PL-3is measured based on the second frame by the switch2 420. Here, thetransmission power information may be included in at least one of theMAC header and the data field 506 of the second frame.

When both of the SNR information and the path loss information of thephysical layer are requested, the end node1 420-1 may perform theforegoing all operations. Also, the end node1 420-1 may determine thestate of the PL-3 based on the measured SNR or path loss of the PL-3.For example, when the SNR of the PL-3 is satisfied with the predefinedquality criterion or the path loss of the PL-3 is satisfied with thepredefined quality criterion, the end node1 420-1 may determine that thestate of the PL-3 is the normal state. In an opposite case to theforegoing description, the end node1 420-1 may determine that the stateof the PL-3 is the fault state. The end node1 420-1 may generate thesecond frame including the determined result of the state of the PL-3.

The end node1 420-1 may transmit the second frame which is generatedbased on the foregoing manner to the switch2 420 (S303).

The switch2 420 may receive the second frame in response to the firstframe from the end node1 420-1 and identify the state of the PL-3 basedon the received second frame. For example, the switch2 420 may obtain atleast one of the SNR information and the path loss information of thePL-3 from the second frame and identify the state (e.g., normal state orfault state) of the PL-3 based on the identified information.Alternatively, when the transmission power information of the secondframe is obtained from the second frame, the switch2 420 may measure thepath loss of the PL-3 based on the obtained information (e.g., thetransmission power information) and identify the state of the PL-3 basedon the measured path loss of the PL-3. Alternatively, when the secondframe in simple response to the first frame is received, the switch2 420may measure the SNR of the PL-3 based on the received second frame andidentify the state of the PL-3 based on the measured SNR of the PL-3.Alternatively, when the second frame includes information indicatingwhether the state of the PL-3 is the normal state or the fault state,the switch2 420 may identify the state of the PL-3 based on theinformation included in the second frame. On the other hand, when thesecond frame in response to the first frame is not received in thepredefined time from the end node1 420-1, the switch2 420 may determinethat the state of the PL-3 is a breaking state (e.g., the PL-3 isbroken).

Meanwhile, the end node2 420-2 may identify that the state informationof the physical layer is requested by receiving the first frame from theswitch2 420. In this case, the end node2 420-2 may operate similar tothe foregoing operations of the end node1 420-1. For example, the endnode2 420-2 may generate the second frame including the stateinformation (e.g., SNR information, path loss information, informationindicating the normal state, information indicating the fault state,etc.) of the PL-4 or information used for measuring the path loss of thePL-4. Alternatively, the end node2 420-2 may generate the second framein simple response to the first frame. The end node2 420-2 may transmitthe generated second frame to the switch2 420 (S304).

The switch2 420 may receive the second frame in response to the firstframe from the end node2 420-2 and identify the state of the PL-4 basedon the received second frame. For example, the switch2 420 may identifythe state of the PL-4 similar to the foregoing method for identifyingthe state of the PL-3. On the other hand, when the second frame inresponse to the first frame is not received in the predefined time fromthe end node2 420-2, the switch2 420 may determine that the state of thePL-4 is the breaking state (e.g., the PL-4 is broken).

Meanwhile, the switch4 440 may identify that the state information ofthe physical layer is requested by receiving the first frame from theswitch2 420. In this case, the switch4 440 may operate similar to theforegoing operations of the switch2 420. For example, the switch4 440may generate the second frame including the state information (e.g., SNRinformation, path loss information, information indicating the normalstate, information indicating the fault state, etc.) of the PL-5 orinformation used for measuring the path loss of the PL-5. Alternatively,the switch4 440 may generate the second frame in simple response to thefirst frame. The switch4 440 may transmit the generated second frame tothe switch2 420 (S305).

The switch2 420 may receive the second frame in response to the firstframe from the switch4 440 and identify the state of the PL-5 based onthe received second frame. For example, the switch2 420 may identify thestate of the PL-5 similar to the foregoing method for identifying thestate of the PL-1. On the other hand, when the second frame in responseto the first frame is not received in the predefined time from theswitch4 440, the switch2 420 may determine that the state of the PL-5 isthe breaking state (e.g., the PL-5 is broken).

After that, the switch2 420 may generate a third frame including thestate information (e.g., SNR information, path loss information,information indicating the normal state, information indicating thefault state) of each of the PL-3, the PL-4, and the PL-5. The stateinformation of each of the PL-3, the PL-4, and the PL-5 may be includedin at least one of the MAC header and the data field 506 of the thirdframe. Alternatively, the switch2 420 may generate the third frameincluding information of the physical layer belonging to the normalstate (or, information of the physical layer belonging to the faultstate). The information of the physical layer belonging to the normalstate (or, information of the physical layer belonging to the faultstate) may be included in at least one of the MAC header and the datafield 506 of the third frame. The switch2 420 may transmit the thirdframe to the switch1 410 (S306). The switch1 410 may receive the thirdframe from the switch2 420 and identify the state of the physical layer(PL-3, PL-4, and PL-5), the physical layer belonging to the normalstate, the physical layer belonging to the fault state, and so on basedon the received third frame (S307).

Meanwhile, after transmitting the second frame to the switch1 410, theswitch3 430 may generate the first frame so at to identify the stateinformation of the physical layer of communication nodes (e.g., endnode3 430-1, end node4 430-2, and switch4 440) which are connected tothe switch3 430. The switch3 430 may transmit the generated first frameto the end node3 430-1, the end node4 430-2, and the switch4 440. Inthis case, the switch3 430 may transmit the first frame in the broadcastmanner or the multicast manner. The first frame may include theindicator requesting the state information of the physical layer. Inaddition, the first frame may further include the transmission powerinformation of the first frame. Here, each of the indicator and thetransmission power information may be included in at least one of theMAC header and the data field 506 of the first frame. The first frametransmitted from the switch3 430 may be identical to the first frametransmitted from the switch1 410.

The end node3 430-1 may identify that the state information of thephysical layer is requested by receiving the first frame from theswitch3 430. In this case, the end node3 430-1 may operate similar tothe foregoing operations of the end node1 420-1. For example, the endnode3 430-1 may generate the second frame including the stateinformation (e.g., SNR information, path loss information, informationindicating the normal state, information indicating the fault state,etc.) of the PL-6 or information used for measuring the path loss of thePL-6. Alternatively, the end node3 430-1 may generate the second framein simple response to the first frame. The end node3 430-1 may transmitthe generated second frame to the switch3 430.

The switch3 430 may receive the second frame in response to the firstframe from the end node3 430-1 and identify the state of the PL-6 basedon the received second frame. For example, the switch3 430 may identifythe state of the PL-6 similar to the foregoing method for identifyingthe state of the PL-3. On the other hand, when the second frame inresponse to the first frame is not received in the predefined time fromthe end node3 430-1, the switch3 430 may determine that the state of thePL-6 is the breaking state (e.g., the PL-6 is broken).

Meanwhile, the end node4 430-2 may identify that the state informationof the physical layer is requested by receiving the first frame from theswitch3 430. In this case, the end node4 430-2 may operate similar tothe foregoing operations of the end node1 420-1. For example, the endnode4 430-2 may generate the second frame including the stateinformation (e.g., SNR information, path loss information, informationindicating the normal state, information indicating the fault state,etc.) of the PL-7 or information used for measuring the path loss of thePL-7. Alternatively, the end node4 430-2 may generate the second framein simple response to the first frame. The end node4 430-2 may transmitthe generated second frame to the switch3 430.

The switch3 430 may receive the second frame in response to the firstframe from the end node4 430-2 and identify the state of the PL-7 basedon the received second frame. For example, the switch3 430 may identifythe state of the PL-7 similar to the foregoing method for identifyingthe state of the PL-3. On the other hand, when the second frame inresponse to the first frame is not received in the predefined time fromthe end node4 430-2, the switch3 430 may determine that the state of thePL-7 is the breaking state (e.g., the PL-7 is broken).

Meanwhile, the switch4 440 may identify that the state information ofthe physical layer is requested by receiving the first frame from theswitch3 430. In this case, the switch4 440 may operate similar to theforegoing operations of the switch2 420. For example, the switch4 440may generate the second frame including the state information (e.g., SNRinformation, path loss information, information indicating the normalstate, information indicating the fault state, etc.) of the PL-8 orinformation used for measuring the path loss of the PL-8. Alternatively,the switch4 440 may generate the second frame in simple response to thefirst frame. The switch4 440 may transmit the generated second frame tothe switch3 430.

The switch3 430 may receive the second frame in response to the firstframe from the switch4 440 and identify the state of the PL-8 based onthe received second frame. For example, the switch3 430 may identify thestate of the PL-8 similar to the foregoing method for identifying thestate of the PL-3. On the other hand, when the second frame in responseto the first frame is not received in the predefined time from theswitch4 440, the switch3 430 may determine that the state of the PL-8 isthe breaking state (e.g., the PL-8 is broken).

After that, the switch3 430 may generate the third frame including thestate information of each of the PL-6, the PL-7, and the PL-8. The stateinformation of each of the PL-6, the PL-7, and the PL-8 may be includedin at least one of the MAC header and the data field 506 of the thirdframe. Alternatively, the switch3 430 may generate the third frameincluding information of the physical layer belonging to the normalstate (or, information of the physical layer belonging to the faultstate). The information of the physical layer belonging to the normalstate (or, information of the physical layer belonging to the faultstate) may be included in at least one of the MAC header and the datafield 506 of the third frame. The switch3 430 may transmit the thirdframe to the switch1 410. The switch1 410 may receive the third framefrom the switch3 430 and identify the state of the physical layer (PL-6,PL-7, and PL-8), the physical layer belonging to the normal state, thephysical layer belonging to the fault state, and so on based on thereceived third frame (S307).

Meanwhile, after transmitting the second frame to at least one of theswitch2 420 and the switch3 430, the switch4 440 may generate the firstframe requesting the state information of the physical layer andtransmit the generated first frame to the end node5 440-1 and the endnode6 440-2. In this case, the switch4 440 may transmit the first framein the broadcast manner or the multicast manner. The first frame mayinclude the indicator requesting the state information of the physicallayer. In addition, the first frame may further include the transmissionpower information of the first frame. Here, each of the indicator andthe transmission power information may be included in at least one ofthe MAC header and the data field 506 of the first frame. The firstframe transmitted from the switch4 440 may be identical to the firstframe transmitted from the switch1 410.

The end node5 440-1 may identify that the state information of thephysical layer is requested by receiving the first frame from theswitch4 440. In this case, the end node5 440-1 may operate similar tothe foregoing operations of the end node1 420-1. For example, the endnode5 440-1 may generate the second frame including the stateinformation (e.g., SNR information, path loss information, informationindicating the normal state, information indicating the fault state,etc.) of the PL-9 or information used for measuring the path loss of thePL-9. Alternatively, the end node5 440-1 may generate the second framein simple response to the first frame. The end node5 440-1 may transmitthe generated second frame to the switch4 440.

The switch4 440 may receive the second frame in response to the firstframe from the end node5 440-1 and identify the state of the PL-9 basedon the received second frame. For example, the switch4 440 may identifythe state of the PL-9 similar to the foregoing method for identifyingthe state of the PL-1. On the other hand, when the second frame inresponse to the first frame is not received in the predefined time fromthe end node5 440-1, the switch4 440 may determine that the state of thePL-9 is the breaking state (e.g., the PL-9 is broken).

Meanwhile, the end node6 440-2 may identify that the state informationof the physical layer is requested by receiving the first frame from theswitch4 440. In this case, the end node6 440-2 may operate similar tothe foregoing operations of the end node1 420-1. For example, the endnode6 440-2 may generate the second frame including the stateinformation (e.g., SNR information, path loss information, informationindicating the normal state, information indicating the fault state,etc.) of the PL-10 or information used for measuring the path loss ofthe PL-10. Alternatively, the end node6 440-2 may generate the secondframe in simple response to the first frame. The end node6 440-2 maytransmit the generated second frame to the switch4 440.

The switch4 440 may receive the second frame in response to the firstframe from the end node6 440-2 and identify the state of the PL-10 basedon the received second frame. For example, the switch4 440 may identifythe state of the PL-10 similar to the foregoing method for identifyingthe state of the PL-1. On the other hand, when the second frame inresponse to the first frame is not received in the predefined time fromthe end node6 440-2, the switch4 440 may determine that the state of thePL-10 is the breaking state (e.g., the PL-10 is broken).

After that, the switch4 440 may generate the third frame including thestate information of each of the PL-9 and the PL-10. The stateinformation of each of the PL-9 and the PL-10 may be included in atleast one of the MAC header and the data field 506 of the third frame.Alternatively, the switch4 440 may generate the third frame includinginformation of the physical layer belonging to the normal state (or,information of the physical layer belonging to the fault state). Theinformation of the physical layer belonging to the normal state (or,information of the physical layer belonging to the fault state) may beincluded in at least one of the MAC header and the data field 506 of thethird frame. The switch4 440 may transmit the third frame to at leastone of the switch2 420 and the switch3 430. When the third frame isreceived from the switch4 440, each of the switch2 420 and the switch3430 may transmit the third frame to the switch1 410. When the thirdframe is received from the switch2 420 or the switch3 430, the switch1410 may identify the state of the physical layer (PL-9 and PL-10), thephysical layer belonging to the normal state, the physical layerbelonging to the fault state, and so on based on the received thirdframe (S307).

As foregoing operations, the switch1 410 may identify the state of thephysical layer (e.g., PL-1, PL-2, PL-3, PL-4, PL-5, PL-6, PL-7, PL-8,PL-9, and PL-10) and set the communication path based on the state ofthe physical layer (S308). For example, in a case that the communicationpath between the switch1 410 and the end node5 440-1 is set to“PL-1-PL-5-PL-9,” the switch1 410 may reset the communication pathbetween the switch1 410 and the end node5 440-1 to “PL-2-PL-8-PL-9” whenthe PL-5 is broken or the state of the PL-5 is not satisfied with thepredefined quality criterion.

Meanwhile, the OBD device 400 may transmit a fourth frame requesting thestate information of the physical layer to the switch1 410 (S309). Here,the OBD device 440 may transmit the fourth frame to the switch1 410periodically or non-periodically. The fourth frame may include theindicator requesting the state information of the physical layer. Theindicator may be included in at least one of the MAC header and the datafield 506 of the fourth frame. When the fourth frame is received fromthe OBD device 400, the switch1 410 may generate a fifth frame includingthe state information of the physical layer (e.g., PL-1, PL-2, PL-3,PL-4, PL-5, PL-6, PL-7, PL-8, PL-9, and PL-10), information of thephysical layer belonging to the normal state, or information of thephysical layer belonging to the fault state and transmit the generatedfifth frame to the OBD device 400 (S310). The OBD device 400 may receivethe fifth frame from the switch1 410 and identify the state of thephysical layer (e.g., PL-1, PL-2, PL-3, PL-4, PL-5, PL-6, PL-7, PL-8,PL-9, and PL-10) based on the information included in the received fifthframe.

The methods according to embodiments of the present disclosure may beimplemented as program instructions executable by a variety of computersand recorded on a computer readable medium. The computer readable mediummay include a program instruction, a data file, a data structure, or acombination thereof. The program instructions recorded on the computerreadable medium may be designed and configured specifically for thepresent disclosure or can be publicly known and available to those whoare skilled in the field of computer software.

Examples of the computer readable medium may include a hardware devicesuch as ROM, RAM, and flash memory, which are specifically configured tostore and execute the program instructions. Examples of the programinstructions include machine codes made by, for example, a compiler, aswell as high-level language codes executable by a computer, using aninterpreter. The above exemplary hardware device can be configured tooperate as at least one software module in order to perform theoperation of the present disclosure, and vice versa.

While the embodiments of the present disclosure and their advantageshave been described in detail above, it should be understood thatvarious changes, substitutions and alterations may be made hereinwithout departing from the scope of the disclosure.

What is claimed is:
 1. An operation method of a first communication nodein an Ethernet-based vehicle network, the method comprising:transmitting, by the first communication node to at least onecommunication node which is connected to the first communication node, afirst frame requesting state information of a physical layer between thefirst communication node and the at least one communication node;receiving, by the first communication node from the at least onecommunication node, a second frame in response to the first frame; andidentifying, by the first communication node, a state of the physicallayer based on the second frame when the second frame is received. 2.The method according to claim 1, wherein the state information is atleast one of signal to noise ratio (SNR) information and path lossinformation of the physical layer.
 3. The method according to claim 1,wherein the first frame includes an indicator requesting the stateinformation of the physical layer.
 4. The method according to claim 1,wherein the first frame includes transmission power information of thefirst frame.
 5. The method according to claim 1, wherein the first frameis transmitted in a broadcast manner.
 6. The method according to claim1, wherein the second frame includes at least one of SNR information andpath loss information of the physical layer, and the SNR information andthe path loss information are measured based on the first frame.
 7. Themethod according to claim 1, wherein the second frame includestransmission power information of the second frame.
 8. The methodaccording to claim 1, wherein the first frame is transmitted whentransmission of the state information of the physical layer is requestedby an on-board diagnostic (OBD) device which is connected to the firstcommunication node.
 9. The method according to claim 1, wherein each ofthe first frame and the second frame is generated based on an Ethernetprotocol.
 10. The method according to claim 1, further comprisingtransmitting, by the first communication node, a third frame includingthe identified state information of the physical layer to an OBD device.11. The method according to claim 1, further comprising: determining, bythe first communication node, whether the identified state of thephysical layer is satisfied with a predefined quality criterion; andwhen the identified state of the physical layer is not satisfied withthe predefined quality criterion, transmitting, by the firstcommunication node, a third frame including information of the physicallayer which is not satisfied with the predefined quality criterion to anOBD device.
 12. The method according to claim 1, further comprising:determining, by the first communication node, whether the identifiedstate of the physical layer is satisfied with a predefined qualitycriterion; and when the identified state of the physical layer is notsatisfied with the predefined quality criterion, setting, by the firstcommunication node, a communication path based on at least one physicallayer except for the physical layer which is not satisfied with thepredefined quality criterion.
 13. An operation method of a firstcommunication node in an Ethernet-based vehicle network, the methodcomprising: receiving, by the first communication node from a secondcommunication node, a first frame requesting state information of aphysical layer between the first communication node and the secondcommunication node; and transmitting, by the first communication node, asecond frame including state information of the physical layer to thesecond communication node when the first frame is received.
 14. Themethod according to claim 13, wherein the state information is at leastone of signal to noise ratio (SNR) information and path loss informationof the physical layer.
 15. The method according to claim 13, wherein thefirst frame includes an indicator requesting the state information ofthe physical layer.
 16. The method according to claim 13, wherein firstframe includes transmission power information of the first frame. 17.The method according to claim 13, wherein the second frame includes atleast one of SNR information and path loss information of the physicallayer, and the SNR information and the path loss information aremeasured based on the first frame.
 18. The method according to claim 13,wherein the second frame includes transmission power information of thesecond frame.
 19. The method according to claim 13, wherein the secondcommunication is a switch, and the first communication node is an endnode connected to the switch.
 20. The method according to claim 13,wherein each of the first frame and the second frame is generated basedon an Ethernet protocol.